Testifying from the grave: Yes, it's pretty rare

Julie Jensen, a 40-year-old mother of two, was found dead, poisoned to death, in her home in Pleasant Prairie, Wisconsin.

Julie Jensen with her four brothers, from left, Patrick, Michael, Paul and Larry.

It turns out that Julie left a note with a neighbor saying that if she were to turn up dead, her husband Mark should be the lead suspect.

So is the note admissible in evidence during her husband's murder trial? Under the traditional rules of hearsay evidence, the answer would be no - because Mark Jensen's lawyer would have no one to cross-examine about the note.

But the Wisconsin Supreme Court said yes, the letter could be received in evidence, under a novel theory... basically that there is probable cause to believe that Mark Jensen had something to do with Julie Jensen's inability to testify. (Read the Wisconsin Supreme Court's opinion)

It's an interesting legal mystery. CNN's Gary Tuchman went to Wisconsin to cover the story, and Anderson and I will discuss the issue tonight on 360.

Jeffrey Toobin, 360° Contributor